Application Of Non Precious Metal Heterojunction Catalysts In Electrocatalytic Tatal Hydrolysis Water

With the economic development,the energy problem is becoming more prominent and acute.Due to the excessive development of fossil fuels,environmental degradation and inadequate utilization of resources are caused.Reducing the use of fossil energy,reducing the release of greenhouse gases and finding alternative energy for sustainable development are effective ways to solve this problem.Compared with other fuels,hydrogen has a relatively high energy density,so it is a promising alternative to meet current and future energy needs.Among hydrogen production technologies,hydrogen production by electrolysis of water is a green and promising hydrogen production technology.At present,the development of alkaline electrolyzer is limited by the high overpotential of HER and OER,resulting in the actual voltage of water decomposition much higher than 1.23 V.At present,the benchmark catalyst of HER is Pt based catalyst,while the basic catalyst of OER is Ru or Ir compound,which severely limited the practical applications of electrolyzed water due to their high cost and extremely low earth reserves.Therefore,it is extremely important to develop non noble metal,especially non noble metal bifunctional catalysts,which can simplify equipment and greatly reduce production costs.In this paper,foam nickel was used as a framework to prepare Ni₃N-CeO₂heterojunction as a bifunctional catalyst for HER and OER.The main research contents are:（1）The precursor of Ni（OH）₂-CeO₂/NF was prepared on the base of foam nickel by hydrothermal method,and then the Ni₃N-CeO₂/NF bifunctional catalyst was prepared by low-temperature nitridation at350℃.Ni₃N-CeO₂/NF electrocatalyst exhibits excellent HER and OER performance.In the hydrogen evolution reaction of 1M KOH,only takes30 m V to achieve a current density of 10 m A cm^-2;In the oxygen evolution reaction of 1M KOH,a current density of 50 m A cm^-2is generated,which only requires 344 m V.（2）Ni₃N-CeO₂/NF is used as a bifunctional catalyst to conduct water splitting in an alkaline electrolytic cell as cathode and anode respectively.Only 1.515 V is needed to provide a current density of 10 m A cm^-2.In addition,the catalyst has fairish catalytic stability.Through in-situ infrared spectroscopy,it was found that the introduction of CeO₂optimized the structure of interfacial water and promoted the adsorption of H₂O molecules.Through DFT calculation and in-situ Raman spectroscopy,the synergistic effect yielded by strong interaction of Ni₃N and CeO₂not only brings adsorption energy of H closer to zero,but also weakens the adsorption of*OH,thereby improving the HER activity,while in the process of OER,the introduction of CeO₂is conducive to the reconstruction of Ni₃N to generate Ni OOH with more O vacancies,and the real active site is Ni OOH-O_vCeO₂.This work systematically explored the mechanism of CeO₂as a cocatalyst to improve the catalytic performance of Ni₃N in the process of alkaline HER and OER,providing insights for the design of high-performance non noble metal heterojunction catalysts.